
"""IMAP4 client.

Based on RFC 2060.

Author: Piers Lauder <piers@cs.su.oz.au> December 1997.

Authentication code contributed by Donn Cave <donn@u.washington.edu> June 1998.

Public class:		IMAP4
Public variable:	Debug
Public functions:	Internaldate2tuple
			Int2AP
			ParseFlags
			Time2Internaldate
"""

__version__ = "2.11"

import binascii, re, socket, string, time, random

#	Globals

CRLF = '\r\n'
Debug = 0
IMAP4_PORT = 143
AllowedVersions = ('IMAP4REV1', 'IMAP4')	# Most recent first

#	Commands

Commands = {
	# name		  valid states
	'APPEND':	('AUTH', 'SELECTED'),
	'AUTHENTICATE':	('NONAUTH',),
	'CAPABILITY':	('NONAUTH', 'AUTH', 'SELECTED', 'LOGOUT'),
	'CHECK':	('SELECTED',),
	'CLOSE':	('SELECTED',),
	'COPY':		('SELECTED',),
	'CREATE':	('AUTH', 'SELECTED'),
	'DELETE':	('AUTH', 'SELECTED'),
	'EXAMINE':	('AUTH', 'SELECTED'),
	'EXPUNGE':	('SELECTED',),
	'FETCH':	('SELECTED',),
	'LIST':		('AUTH', 'SELECTED'),
	'LOGIN':	('NONAUTH',),
	'LOGOUT':	('NONAUTH', 'AUTH', 'SELECTED', 'LOGOUT'),
	'LSUB':		('AUTH', 'SELECTED'),
	'NOOP':		('NONAUTH', 'AUTH', 'SELECTED', 'LOGOUT'),
	'PARTIAL':	('SELECTED',),
	'RENAME':	('AUTH', 'SELECTED'),
	'SEARCH':	('SELECTED',),
	'SELECT':	('AUTH', 'SELECTED'),
	'STATUS':	('AUTH', 'SELECTED'),
	'STORE':	('SELECTED',),
	'SUBSCRIBE':	('AUTH', 'SELECTED'),
	'UID':		('SELECTED',),
	'UNSUBSCRIBE':	('AUTH', 'SELECTED'),
	}

#	Patterns to match server responses

Continuation = re.compile(r'\+( (?P<data>.*))?')
Flags = re.compile(r'.*FLAGS \((?P<flags>[^\)]*)\)')
InternalDate = re.compile(r'.*INTERNALDATE "'
	r'(?P<day>[ 123][0-9])-(?P<mon>[A-Z][a-z][a-z])-(?P<year>[0-9][0-9][0-9][0-9])'
	r' (?P<hour>[0-9][0-9]):(?P<min>[0-9][0-9]):(?P<sec>[0-9][0-9])'
	r' (?P<zonen>[-+])(?P<zoneh>[0-9][0-9])(?P<zonem>[0-9][0-9])'
	r'"')
Literal = re.compile(r'(?P<data>.*) {(?P<size>\d+)}$')
Response_code = re.compile(r'\[(?P<type>[A-Z-]+)( (?P<data>[^\]]*))?\]')
Untagged_response = re.compile(r'\* (?P<type>[A-Z-]+)( (?P<data>.*))?')
Untagged_status = re.compile(r'\* (?P<data>\d+) (?P<type>[A-Z-]+)( (?P<data2>.*))?')


class IMAP4:

	"""IMAP4 client class.

	Instantiate with: IMAP4([host[, port]])

		host - host's name (default: localhost);
		port - port number (default: standard IMAP4 port).

	All IMAP4rev1 commands are supported by methods of the same
	name (in lower-case).

	All arguments to commands are converted to strings, except for
	AUTHENTICATE, and the last argument to APPEND which is passed as
	an IMAP4 literal.  If necessary (the string contains
	white-space and isn't enclosed with either parentheses or
	double quotes) each string is quoted.

	Each command returns a tuple: (type, [data, ...]) where 'type'
	is usually 'OK' or 'NO', and 'data' is either the text from the
	tagged response, or untagged results from command.

	Errors raise the exception class <instance>.error("<reason>").
	IMAP4 server errors raise <instance>.abort("<reason>"),
	which is a sub-class of 'error'.

	Note: to use this module, you must read the RFCs pertaining
	to the IMAP4 protocol, as the semantics of the arguments to
	each IMAP4 command are left to the invoker, not to mention
	the results.
	"""

	class error(Exception): pass	# Logical errors - debug required
	class abort(error): pass	# Service errors - close and retry


	def __init__(self, host = '', port = IMAP4_PORT):
		self.host = host
		self.port = port
		self.debug = Debug
		self.state = 'LOGOUT'
		self.literal = None		# A literal argument to a command
		self.tagged_commands = {}	# Tagged commands awaiting response
		self.untagged_responses = {}	# {typ: [data, ...], ...}
		self.continuation_response = ''	# Last continuation response
		self.tagnum = 0

		# Open socket to server.

		self.open(host, port)

		# Create unique tag for this session,
		# and compile tagged response matcher.

		self.tagpre = Int2AP(random.randint(0, 31999))
		self.tagre = re.compile(r'(?P<tag>'
				+ self.tagpre
				+ r'\d+) (?P<type>[A-Z]+) (?P<data>.*)')

		# Get server welcome message,
		# request and store CAPABILITY response.

		if __debug__ and self.debug >= 1:
			print '\tnew IMAP4 connection, tag=%s' % self.tagpre

		self.welcome = self._get_response()
		if self.untagged_responses.has_key('PREAUTH'):
			self.state = 'AUTH'
		elif self.untagged_responses.has_key('OK'):
			self.state = 'NONAUTH'
#		elif self.untagged_responses.has_key('BYE'):
		else:
			raise self.error(self.welcome)

		cap = 'CAPABILITY'
		self._simple_command(cap)
		if not self.untagged_responses.has_key(cap):
			raise self.error('no CAPABILITY response from server')
		self.capabilities = tuple(string.split(self.untagged_responses[cap][-1]))

		if __debug__ and self.debug >= 3:
			print '\tCAPABILITIES: %s' % `self.capabilities`

		for version in AllowedVersions:
			if not version in self.capabilities:
				continue
			self.PROTOCOL_VERSION = version
			return

		raise self.error('server not IMAP4 compliant')


	def open(self, host, port):
		"""Setup 'self.sock' and 'self.file'."""
		self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
		self.sock.connect(self.host, self.port)
		self.file = self.sock.makefile('r')


	def __getattr__(self, attr):
		"""Allow UPPERCASE variants of all following IMAP4 commands."""
		if Commands.has_key(attr):
			return eval("self.%s" % string.lower(attr))
		raise AttributeError("Unknown IMAP4 command: '%s'" % attr)


	#	Public methods


	def append(self, mailbox, flags, date_time, message):
		"""Append message to named mailbox.

		(typ, [data]) = <instance>.append(mailbox, flags, date_time, message)
		"""
		name = 'APPEND'
		if flags:
			if (flags[0],flags[-1]) != ('(',')'):
				flags = '(%s)' % flags
		else:
			flags = None
		if date_time:
			date_time = Time2Internaldate(date_time)
		else:
			date_time = None
		self.literal = message
		return self._simple_command(name, mailbox, flags, date_time)


	def authenticate(self, mechanism, authobject):
		"""Authenticate command - requires response processing.

		'mechanism' specifies which authentication mechanism is to
		be used - it must appear in <instance>.capabilities in the
		form AUTH=<mechanism>.

		'authobject' must be a callable object:

			data = authobject(response)

		It will be called to process server continuation responses.
		It should return data that will be encoded and sent to server.
		It should return None if the client abort response '*' should
		be sent instead.
		"""
		mech = string.upper(mechanism)
		cap = 'AUTH=%s' % mech
		if not cap in self.capabilities:
			raise self.error("Server doesn't allow %s authentication." % mech)
		self.literal = _Authenticator(authobject).process
		typ, dat = self._simple_command('AUTHENTICATE', mech)
		if typ != 'OK':
			raise self.error(dat)
		self.state = 'AUTH'
		return typ, dat


	def check(self):
		"""Checkpoint mailbox on server.

		(typ, [data]) = <instance>.check()
		"""
		return self._simple_command('CHECK')


	def close(self):
		"""Close currently selected mailbox.

		Deleted messages are removed from writable mailbox.
		This is the recommended command before 'LOGOUT'.

		(typ, [data]) = <instance>.close()
		"""
		try:
			try: typ, dat = self._simple_command('CLOSE')
			except EOFError: typ, dat = None, [None]
		finally:
			self.state = 'AUTH'
		return typ, dat


	def copy(self, message_set, new_mailbox):
		"""Copy 'message_set' messages onto end of 'new_mailbox'.

		(typ, [data]) = <instance>.copy(message_set, new_mailbox)
		"""
		return self._simple_command('COPY', message_set, new_mailbox)


	def create(self, mailbox):
		"""Create new mailbox.

		(typ, [data]) = <instance>.create(mailbox)
		"""
		return self._simple_command('CREATE', mailbox)


	def delete(self, mailbox):
		"""Delete old mailbox.

		(typ, [data]) = <instance>.delete(mailbox)
		"""
		return self._simple_command('DELETE', mailbox)


	def expunge(self):
		"""Permanently remove deleted items from selected mailbox.

		Generates 'EXPUNGE' response for each deleted message.

		(typ, [data]) = <instance>.expunge()

		'data' is list of 'EXPUNGE'd message numbers in order received.
		"""
		name = 'EXPUNGE'
		typ, dat = self._simple_command(name)
		return self._untagged_response(typ, name)


	def fetch(self, message_set, message_parts):
		"""Fetch (parts of) messages.

		(typ, [data, ...]) = <instance>.fetch(message_set, message_parts)

		'data' are tuples of message part envelope and data.
		"""
		name = 'FETCH'
		typ, dat = self._simple_command(name, message_set, message_parts)
		return self._untagged_response(typ, name)


	def list(self, directory='""', pattern='*'):
		"""List mailbox names in directory matching pattern.

		(typ, [data]) = <instance>.list(directory='""', pattern='*')

		'data' is list of LIST responses.
		"""
		name = 'LIST'
		typ, dat = self._simple_command(name, directory, pattern)
		return self._untagged_response(typ, name)


	def login(self, user, password):
		"""Identify client using plaintext password.

		(typ, [data]) = <instance>.list(user, password)
		"""
		typ, dat = self._simple_command('LOGIN', user, password)
		if typ != 'OK':
			raise self.error(dat)
		self.state = 'AUTH'
		return typ, dat


	def logout(self):
		"""Shutdown connection to server.

		(typ, [data]) = <instance>.logout()

		Returns server 'BYE' response.
		"""
		self.state = 'LOGOUT'
		try: typ, dat = self._simple_command('LOGOUT')
		except EOFError: typ, dat = None, [None]
		self.file.close()
		self.sock.close()
		if self.untagged_responses.has_key('BYE'):
			return 'BYE', self.untagged_responses['BYE']
		return typ, dat


	def lsub(self, directory='""', pattern='*'):
		"""List 'subscribed' mailbox names in directory matching pattern.

		(typ, [data, ...]) = <instance>.lsub(directory='""', pattern='*')

		'data' are tuples of message part envelope and data.
		"""
		name = 'LSUB'
		typ, dat = self._simple_command(name, directory, pattern)
		return self._untagged_response(typ, name)


	def noop(self):
		"""Send NOOP command.

		(typ, data) = <instance>.noop()
		"""
		if __debug__ and self.debug >= 3:
			print '\tuntagged responses: %s' % `self.untagged_responses`
		return self._simple_command('NOOP')


	def partial(self, message_num, message_part, start, length):
		"""Fetch truncated part of a message.

		(typ, [data, ...]) = <instance>.partial(message_num, message_part, start, length)

		'data' is tuple of message part envelope and data.
		"""
		name = 'PARTIAL'
		typ, dat = self._simple_command(name, message_num, message_part, start, length)
		return self._untagged_response(typ, 'FETCH')


	def recent(self):
		"""Return most recent 'RECENT' responses if any exist,
		else prompt server for an update using the 'NOOP' command,
		and flush all untagged responses.

		(typ, [data]) = <instance>.recent()

		'data' is None if no new messages,
		else list of RECENT responses, most recent last.
		"""
		name = 'RECENT'
		typ, dat = self._untagged_response('OK', name)
		if dat[-1]:
			return typ, dat
		self.untagged_responses = {}
		typ, dat = self._simple_command('NOOP')
		return self._untagged_response(typ, name)


	def rename(self, oldmailbox, newmailbox):
		"""Rename old mailbox name to new.

		(typ, data) = <instance>.rename(oldmailbox, newmailbox)
		"""
		return self._simple_command('RENAME', oldmailbox, newmailbox)


	def response(self, code):
		"""Return data for response 'code' if received, or None.

		Old value for response 'code' is cleared.

		(code, [data]) = <instance>.response(code)
		"""
		return self._untagged_response(code, string.upper(code))


	def search(self, charset, criteria):
		"""Search mailbox for matching messages.

		(typ, [data]) = <instance>.search(charset, criteria)

		'data' is space separated list of matching message numbers.
		"""
		name = 'SEARCH'
		if charset:
			charset = 'CHARSET ' + charset
		typ, dat = self._simple_command(name, charset, criteria)
		return self._untagged_response(typ, name)


	def select(self, mailbox='INBOX', readonly=None):
		"""Select a mailbox.

		Flush all untagged responses.

		(typ, [data]) = <instance>.select(mailbox='INBOX', readonly=None)

		'data' is count of messages in mailbox ('EXISTS' response).
		"""
		# Mandated responses are ('FLAGS', 'EXISTS', 'RECENT', 'UIDVALIDITY')
		self.untagged_responses = {}	# Flush old responses.
		if readonly:
			name = 'EXAMINE'
		else:
			name = 'SELECT'
		typ, dat = self._simple_command(name, mailbox)
		if typ == 'OK':
			self.state = 'SELECTED'
		elif typ == 'NO':
			self.state = 'AUTH'
		if not readonly and not self.untagged_responses.has_key('READ-WRITE'):
			raise self.error('%s is not writable' % mailbox)
		return typ, self.untagged_responses.get('EXISTS', [None])


	def socket(self):
		"""Return socket instance used to connect to IMAP4 server.

		socket = <instance>.socket()
		"""
		return self.sock


	def status(self, mailbox, names):
		"""Request named status conditions for mailbox.

		(typ, [data]) = <instance>.status(mailbox, names)
		"""
		name = 'STATUS'
		if self.PROTOCOL_VERSION == 'IMAP4':
			raise self.error('%s unimplemented in IMAP4 (obtain IMAP4rev1 server, or re-code)' % name)
		typ, dat = self._simple_command(name, mailbox, names)
		return self._untagged_response(typ, name)


	def store(self, message_set, command, flag_list):
		"""Alters flag dispositions for messages in mailbox.

		(typ, [data]) = <instance>.store(message_set, command, flag_list)
		"""
		typ, dat = self._simple_command('STORE', message_set, command, flag_list)
		return self._untagged_response(typ, 'FETCH')


	def subscribe(self, mailbox):
		"""Subscribe to new mailbox.

		(typ, [data]) = <instance>.subscribe(mailbox)
		"""
		return self._simple_command('SUBSCRIBE', mailbox)


	def uid(self, command, *args):
		"""Execute "command arg ..." with messages identified by UID,
			rather than message number.

		(typ, [data]) = <instance>.uid(command, arg1, arg2, ...)

		Returns response appropriate to 'command'.
		"""
		command = string.upper(command)
		if not Commands.has_key(command):
			raise self.error("Unknown IMAP4 UID command: %s" % command)
		if self.state not in Commands[command]:
			raise self.error('command %s illegal in state %s'
						% (command, self.state))
		name = 'UID'
		typ, dat = apply(self._simple_command, (name, command) + args)
		if command == 'SEARCH':
			name = 'SEARCH'
		else:
			name = 'FETCH'
		typ, dat2 = self._untagged_response(typ, name)
		if dat2[-1]: dat = dat2
		return typ, dat


	def unsubscribe(self, mailbox):
		"""Unsubscribe from old mailbox.

		(typ, [data]) = <instance>.unsubscribe(mailbox)
		"""
		return self._simple_command('UNSUBSCRIBE', mailbox)


	def xatom(self, name, *args):
		"""Allow simple extension commands
			notified by server in CAPABILITY response.

		(typ, [data]) = <instance>.xatom(name, arg, ...)
		"""
		if name[0] != 'X' or not name in self.capabilities:
			raise self.error('unknown extension command: %s' % name)
		return apply(self._simple_command, (name,) + args)


	#	Private methods


	def _append_untagged(self, typ, dat):

		ur = self.untagged_responses
		if ur.has_key(typ):
			ur[typ].append(dat)
		else:
			ur[typ] = [dat]
		if __debug__ and self.debug >= 5:
			print '\tuntagged_responses[%s] %s += %s' % (typ, len(`ur[typ]`), _trunc(20, `dat`))


	def _command(self, name, *args):

		if self.state not in Commands[name]:
			self.literal = None
			raise self.error(
			'command %s illegal in state %s' % (name, self.state))

		if self.untagged_responses.has_key('OK'):
			del self.untagged_responses['OK']

		tag = self._new_tag()
		data = '%s %s' % (tag, name)
		for d in args:
			if d is None: continue
			if type(d) is type(''):
				l = len(string.split(d))
			else:
				l = 1
			if l == 0 or l > 1 and (d[0],d[-1]) not in (('(',')'),('"','"')):
				data = '%s "%s"' % (data, d)
			else:
				data = '%s %s' % (data, d)

		literal = self.literal
		if literal is not None:
			self.literal = None
			if type(literal) is type(self._command):
				literator = literal
			else:
				literator = None
				data = '%s {%s}' % (data, len(literal))

		try:
			self.sock.send('%s%s' % (data, CRLF))
		except socket.error, val:
			raise self.abort('socket error: %s' % val)

		if __debug__ and self.debug >= 4:
			print '\t> %s' % data

		if literal is None:
			return tag

		while 1:
			# Wait for continuation response

			while self._get_response():
				if self.tagged_commands[tag]:	# BAD/NO?
					return tag

			# Send literal

			if literator:
				literal = literator(self.continuation_response)

			if __debug__ and self.debug >= 4:
				print '\twrite literal size %s' % len(literal)

			try:
				self.sock.send(literal)
				self.sock.send(CRLF)
			except socket.error, val:
				raise self.abort('socket error: %s' % val)

			if not literator:
				break

		return tag


	def _command_complete(self, name, tag):
		try:
			typ, data = self._get_tagged_response(tag)
		except self.abort, val:
			raise self.abort('command: %s => %s' % (name, val))
		except self.error, val:
			raise self.error('command: %s => %s' % (name, val))
		if self.untagged_responses.has_key('BYE') and name != 'LOGOUT':
			raise self.abort(self.untagged_responses['BYE'][-1])
		if typ == 'BAD':
			raise self.error('%s command error: %s %s' % (name, typ, data))
		return typ, data


	def _get_response(self):

		# Read response and store.
		#
		# Returns None for continuation responses,
		# otherwise first response line received.

		resp = self._get_line()

		# Command completion response?

		if self._match(self.tagre, resp):
			tag = self.mo.group('tag')
			if not self.tagged_commands.has_key(tag):
				raise self.abort('unexpected tagged response: %s' % resp)

			typ = self.mo.group('type')
			dat = self.mo.group('data')
			self.tagged_commands[tag] = (typ, [dat])
		else:
			dat2 = None

			# '*' (untagged) responses?

			if not self._match(Untagged_response, resp):
				if self._match(Untagged_status, resp):
					dat2 = self.mo.group('data2')

			if self.mo is None:
				# Only other possibility is '+' (continuation) rsponse...

				if self._match(Continuation, resp):
					self.continuation_response = self.mo.group('data')
					return None	# NB: indicates continuation

				raise self.abort("unexpected response: '%s'" % resp)

			typ = self.mo.group('type')
			dat = self.mo.group('data')
			if dat is None: dat = ''	# Null untagged response
			if dat2: dat = dat + ' ' + dat2

			# Is there a literal to come?

			while self._match(Literal, dat):

				# Read literal direct from connection.

				size = string.atoi(self.mo.group('size'))
				if __debug__ and self.debug >= 4:
					print '\tread literal size %s' % size
				data = self.file.read(size)

				# Store response with literal as tuple

				self._append_untagged(typ, (dat, data))

				# Read trailer - possibly containing another literal

				dat = self._get_line()

			self._append_untagged(typ, dat)

		# Bracketed response information?

		if typ in ('OK', 'NO', 'BAD') and self._match(Response_code, dat):
			self._append_untagged(self.mo.group('type'), self.mo.group('data'))

		return resp


	def _get_tagged_response(self, tag):

		while 1:
			result = self.tagged_commands[tag]
			if result is not None:
				del self.tagged_commands[tag]
				return result
			self._get_response()


	def _get_line(self):

		line = self.file.readline()
		if not line:
			raise EOFError

		# Protocol mandates all lines terminated by CRLF

		line = line[:-2]
		if __debug__ and self.debug >= 4:
			print '\t< %s' % line
		return line


	def _match(self, cre, s):

		# Run compiled regular expression match method on 's'.
		# Save result, return success.

		self.mo = cre.match(s)
		if __debug__ and self.mo is not None and self.debug >= 5:
			print "\tmatched r'%s' => %s" % (cre.pattern, `self.mo.groups()`)
		return self.mo is not None


	def _new_tag(self):

		tag = '%s%s' % (self.tagpre, self.tagnum)
		self.tagnum = self.tagnum + 1
		self.tagged_commands[tag] = None
		return tag


	def _simple_command(self, name, *args):

		return self._command_complete(name, apply(self._command, (name,) + args))


	def _untagged_response(self, typ, name):

		if not self.untagged_responses.has_key(name):
			return typ, [None]
		data = self.untagged_responses[name]
		if __debug__ and self.debug >= 5:
			print '\tuntagged_responses[%s] => %s' % (name, _trunc(20, `data`))
		del self.untagged_responses[name]
		return typ, data


class _Authenticator:

	"""Private class to provide en/decoding
		for base64-based authentication conversation.
	"""

	def __init__(self, mechinst):
		self.mech = mechinst	# Callable object to provide/process data

	def process(self, data):
		ret = self.mech(self.decode(data))
		if ret is None:
			return '*'	# Abort conversation
		return self.encode(ret)

	def encode(self, inp):
		#
		#  Invoke binascii.b2a_base64 iteratively with
		#  short even length buffers, strip the trailing
		#  line feed from the result and append.  "Even"
		#  means a number that factors to both 6 and 8,
		#  so when it gets to the end of the 8-bit input
		#  there's no partial 6-bit output.
		#
		oup = ''
		while inp:
			if len(inp) > 48:
				t = inp[:48]
				inp = inp[48:]
			else:
				t = inp
				inp = ''
			e = binascii.b2a_base64(t)
			if e:
				oup = oup + e[:-1]
		return oup
  
	def decode(self, inp):
		if not inp:
			return ''
		return binascii.a2b_base64(inp)
 

Mon2num = {'Jan': 1, 'Feb': 2, 'Mar': 3, 'Apr': 4, 'May': 5, 'Jun': 6,
	'Jul': 7, 'Aug': 8, 'Sep': 9, 'Oct': 10, 'Nov': 11, 'Dec': 12}

def Internaldate2tuple(resp):

	"""Convert IMAP4 INTERNALDATE to UT.

	Returns Python time module tuple.
	"""

	mo = InternalDate.match(resp)
	if not mo:
		return None

	mon = Mon2num[mo.group('mon')]
	zonen = mo.group('zonen')

	for name in ('day', 'year', 'hour', 'min', 'sec', 'zoneh', 'zonem'):
		exec "%s = string.atoi(mo.group('%s'))" % (name, name)

	# INTERNALDATE timezone must be subtracted to get UT

	zone = (zoneh*60 + zonem)*60
	if zonen == '-':
		zone = -zone

	tt = (year, mon, day, hour, min, sec, -1, -1, -1)

	utc = time.mktime(tt)

	# Following is necessary because the time module has no 'mkgmtime'.
	# 'mktime' assumes arg in local timezone, so adds timezone/altzone.

	lt = time.localtime(utc)
	if time.daylight and lt[-1]:
		zone = zone + time.altzone
	else:
		zone = zone + time.timezone

	return time.localtime(utc - zone)


def Int2AP(num):

	"""Convert integer to A-P string representation."""

	val = ''; AP = 'ABCDEFGHIJKLMNOP'
	num = int(abs(num))
	while num:
		num, mod = divmod(num, 16)
		val = AP[mod] + val
	return val


def ParseFlags(resp):

	"""Convert IMAP4 flags response to python tuple."""

	mo = Flags.match(resp)
	if not mo:
		return ()

	return tuple(string.split(mo.group('flags')))


def Time2Internaldate(date_time):

	"""Convert 'date_time' to IMAP4 INTERNALDATE representation.

	Return string in form: '"DD-Mmm-YYYY HH:MM:SS +HHMM"'
	"""

	dttype = type(date_time)
	if dttype is type(1):
		tt = time.localtime(date_time)
	elif dttype is type(()):
		tt = date_time
	elif dttype is type(""):
		return date_time	# Assume in correct format
	else: raise ValueError

	dt = time.strftime("%d-%b-%Y %H:%M:%S", tt)
	if dt[0] == '0':
		dt = ' ' + dt[1:]
	if time.daylight and tt[-1]:
		zone = -time.altzone
	else:
		zone = -time.timezone
	return '"' + dt + " %+02d%02d" % divmod(zone/60, 60) + '"'


if __debug__:

	def _trunc(m, s):
		if len(s) <= m: return s
		return '%.*s..' % (m, s)


if __debug__ and __name__ == '__main__':

	import getpass, sys

	host = ''
	if sys.argv[1:]: host = sys.argv[1]

	USER = getpass.getuser()
	PASSWD = getpass.getpass("IMAP password for %s: " % (host or "localhost"))

	test_seq1 = (
	('login', (USER, PASSWD)),
	('create', ('/tmp/xxx 1',)),
	('rename', ('/tmp/xxx 1', '/tmp/yyy')),
	('CREATE', ('/tmp/yyz 2',)),
	('append', ('/tmp/yyz 2', None, None, 'From: anon@x.y.z\n\ndata...')),
	('select', ('/tmp/yyz 2',)),
	('search', (None, '(TO zork)')),
	('partial', ('1', 'RFC822', 1, 1024)),
	('store', ('1', 'FLAGS', '(\Deleted)')),
	('expunge', ()),
	('recent', ()),
	('close', ()),
	)

	test_seq2 = (
	('select', ()),
	('response',('UIDVALIDITY',)),
	('uid', ('SEARCH', 'ALL')),
	('response', ('EXISTS',)),
	('recent', ()),
	('logout', ()),
	)

	def run(cmd, args):
		typ, dat = apply(eval('M.%s' % cmd), args)
		print ' %s %s\n  => %s %s' % (cmd, args, typ, dat)
		return dat

	Debug = 5
	M = IMAP4(host)
	print 'PROTOCOL_VERSION = %s' % M.PROTOCOL_VERSION

	for cmd,args in test_seq1:
		run(cmd, args)

	for ml in run('list', ('/tmp/', 'yy%')):
		mo = re.match(r'.*"([^"]+)"$', ml)
		if mo: path = mo.group(1)
		else: path = string.split(ml)[-1]
		run('delete', (path,))

	for cmd,args in test_seq2:
		dat = run(cmd, args)

		if (cmd,args) != ('uid', ('SEARCH', 'ALL')):
			continue

		uid = string.split(dat[-1])[-1]
		run('uid', ('FETCH', '%s' % uid,
			'(FLAGS INTERNALDATE RFC822.SIZE RFC822.HEADER RFC822.TEXT)'))